Permeability separatory apparatus or mass transfer devices, including blood oxygenator systems, have been known for some time. U.S. Pat. No. 3,422,008 (to McLain) discloses permeability separatory apparatus and the process of manufacture and use of such apparatus. Hollow fibers of a selectively permeable membrane are wound around a cylindrical core or along a substantial portion of the length of the core. The core is perforated or porous along its length or a substantial portion thereof so a fluid can pass from the interior of the core around or through the fibers wound on the core. Alternatively, the core may be impermeable for applications wherein a high pressure fluid is introduced into the hollow fibers. In each embodiment, a case encloses the core and fibers and provides a region for collecting fluid that has passed around or through the fibers. Although McLain discloses various cases and arrangements for winding fibers on a core (e.g., loose winding, winding fibers directly on the core, or winding fibers on other removable means, then inserting the core), there is no suggestion about providing concentric, radially spaced fluid or blood inlet and outlet manifolds on each side of a fiber bundle to achieve optimal delicate fluid handling characteristics, and the best transfer per unit area.
U.S. Pat. No. 4,424,190 (to Mather, III et al.) discloses a hollow fiber blood oxygenator for supplying oxygen to blood flowing on the outside of a plural layer mat of hollow fibers which carry oxygen inside the fiber lumens. Blood travels upwardly from the bottom end of the oxygenator into a central core with a porous wall, outwardly through the core along the length thereof into and radially through the mat and then into an annular space between the inside of the outer wall of the oxygenator and the outer surface of the mat. A blood outlet for conducting the blood out of the space is at the bottom of the oxygenator.
The Mather, III et al. patent acknowledges it is undesirable to subject blood to unusual mechanically applied forces of stress (e.g., pressure drops) during its flow through an oxygenator, but there is no suggestion about providing a blood flow path wherein the radial flow outwardly from along the axis of a core is substantially the same all along the axis, and wherein the path is at least partially defined by a blood inlet manifold and a blood delivery outlet manifold having substantially equal lengths and volumes.
U.S. Pat. No. 4,975,247 (to Badolato et al.), and corresponding EPO document 0 187 708 B1 (also to Badolato et al.), discloses an axial flow hollow fiber blood oxygenator including a hollow support core around which hollow fibers are wound to form a bundle, and an outer casing. A gas entry port is coupled to the fibers at the first, top end of the bundle and a gas outlet is coupled to the fibers at the second, bottom end of the bundle. A blood inlet is at the bottom end of the bundle and a blood outlet is at the top, thereby providing an axial blood flow through the bundle parallel to the longitudinal axis of the core. Blood is introduced through the inlet and is directed by an angled dish portion of the support core into the bottom of the fiber bundle through a series of apertures. Similarly, blood exits the top of the fiber bundle through openings, flows into an annular blood passage and out a blood outlet. There is no suggestion about how to provide a radial blood flow path through a fiber bundle.
While the oxygenators disclosed in the preceding patents represent advances in the art, and while at least the Mather, III, et al. patent recognizes that it is undesirable to subject blood to unusual mechanically applied forces of stress, such stresses have not been reduced to an optimal level by known oxygenators, nor has gas transfer been optimized. Another problem inadequately addressed, particularly in prior art radial flow oxygenators such as the Mather, III, et al. device, is that blood reaching the blood outlet is not uniformly oxygenated because blood does not flow or dwell uniformly in all regions of the devices.